The present invention is directed to bicycle freewheels and, more particularly, to a pawl noise dampening mechanism for a bicycle freewheel.
The hub of the drive-side wheel (usually the rear wheel) of a bicycle is sometimes provided with an integrated or separate freewheel. The freewheel is usually equipped with a one-way clutch mechanism so that only unidirectional rotational force is transmitted to the bicycle wheel. One-way clutch mechanisms having various structures are known. One known example is a ratchet mechanism in which engagement between pawls and ratchet teeth is employed. When the chain is driven by the pedals and a cog is rotatably driven, the ratchet mechanism transmits the torque from the ratchet teeth to the pawls and rotatably drives an inner component. The pawls are actuated by pawl springs in such a way as to ensure constant engagement with the ratchet teeth. The ratchet mechanism must possess extremely high strength and shock resistance because considerable torque and impact forces are transmitted from the ratchet teeth to the pawls.
When the pedals are stopped or rotated backward, the inner component of the freewheel rotates together with the wheel, creating a rotational movement in relation to the ratchet teeth. Because the inner component has pawls, the pawls and the ratchet teeth move relative to each other. Since the pawls are constantly actuated and pressed against the tooth surfaces of the ratchet teeth by pawl springs, the pawls chatter against the teeth surfaces of the ratchet teeth when performing a rocking movement in conformity with the peaks and valleys of the ratchet teeth. The noise generated by such a ratchet mechanism is unpleasant for the cyclist, and the friction between the pawls and the tooth surfaces of the ratchet teeth wastes energy. The result is that this type of friction wears out the pawls and the tooth surfaces of the ratchet teeth, thus shortening freewheel life.